To begin a challenge, click the "Try Challenge" button. From there, select the challenge you want to attempt. Clicking "Start Challenge" will take you to the starter-pack GitHub repository where you can download the code as a zip file. Once you have opened the repository in VSCode, you will see that there are pre-existing folders and files set up for you. In the repository, there is a file called "your.css" where you can fill in the blank properties and try to complete the challenge on your own. If you ever feel stuck, you can refer to the main repository for solutions.